Use interface operstate to determine nic status
Use interface operstate to determine nic status

Fixes lp bug 1555669

Currently _is_active_nic performs multiple checks to see if a link is live.
However some hardware such as Ethernet over USB devices fulfil this criteria.
This causes tripleo deployments to fail if automatic interface naming is used.
We can therefore use operstate to determine if the link is actually up.
https://www.kernel.org/doc/Documentation/networking/operstates.txt
This patch implements this.

Implements: better link state detection
Closes-Bug: #1555669
Change-Id: I0bdd0c987f4f177935df4f7cdcc70f4d99c988a5
Signed-off-by: Christopher Brown <eb185d661a9aeb72ece21897b5a16c3c4880f948@gmail.com>

openstack/os-net-config